* tyt
  :PROPERTIES:
  :header-args: :tangle tyt :shebang "#!/bin/sh"
  :END:

  Terminal YouTube (*tyt*) is a small bash script that lets you play YouTube videos by query from the command line.
  It is created via literate programming, you can find the code below.

** Script
*** Dependencies

    The dependencies of the script are:

    - [[https://stedolan.github.io/jq/][jq]]
    - [[https://mpv.io/][mpv]]
    - [[https://ytdl-org.github.io/youtube-dl/][youtube-dl]]

    Please make sure those are available on your system.
    If you are using the [[https://nixos.org/][Nix]] package manager, you can run =nix-shell= in the project directory.
    This will drop you into a shell with all requirements fulfilled.

    On the start of the script, it is checked if the dependencies are fulfilled.

    #+begin_src sh
      if ! command -v mpv &> /dev/null
      then
        echo -ne "\e[1mmpv\e[0m was not found, please install it"
	exit 1
      elif ! command -v youtube-dl &> /dev/null
      then
        echo -ne "\e[1myoutube-dl\e[0m was not found, please install it"
	exit 1
      fi
    #+end_src

*** Usage

    This function prints the usage of the script.

    #+begin_src sh
      function print_usage {
        echo "tyt [ -a* | --alternative ] \"QUERY\""
      }
    #+end_src

*** Arguments

    At first we parse the arguments.
    We have the following flags:

    - =a*|alternative= :: Alternative video (optional); You can parse any amount of alternatives (e.g. =-aaa=)

    Additionally we have exacly one mandatory quoted string as query.

    #+begin_src sh
      alternative=0
      format="flac"
      help=false

      for arg in "$@"
      do
        case $arg in
          -a*)
            alternative="${arg:1}"
            alternative="${#alternative}"
            shift
            ;;
          --alternative)
            alternative=1
            shift
            ;;
          -h|--help)
            help=true
            shift
            ;;
          ,*)
            other_arguments+=("$1")
            shift
            ;;
        esac
      done
    
      if [ "$help" = true ]
      then
        print_usage
        exit 0
      fi
    
      if [ "${#other_arguments[@]}" != "1" ]
      then
        print_usage
        exit 1
      fi
    
      query="${other_arguments[0]}"
    #+end_src

*** Greeter

    If the arguments match, print a greeter.

    #+begin_src sh
      echo -ne "\n    \e[1m  \ /\e[0m\n"
      echo -ne "    \e[1m=======\e[0m\n"
      echo -ne "    | \e[31m\e[1mtyt\e[0m |\n"
      echo -ne "    \e[1m=======\e[0m\n\n"
    #+end_src
    
*** Get URL

    To play a video, we need to get a valid URL.
    Since there are sometimes parsing errors of the JSON response, we use an endless loop to try until we get a valid response.
    The first /n/ URLs are saved if an alternative download is requested.

    #+begin_src sh
      i=0
      n=$((alternative+1))
    
      echo -ne "Searching for: \e[33m\e[1m$query\e[0m    \r"
    
      until results=$(youtube-dl --default-search "ytsearch" -j "ytsearch$n:$query") &> /dev/null
      do
    
        case $i in
          0)
    	appendix="   "
    	;;
          1)
    	appendix=".  "
    	;;
          2)
    	appendix=".. "
    	;;
          ,*)
    	appendix="..."
    	;;
        esac
    
        echo -ne "Searching for: \e[33m\e[1m$query\e[0m $appendix\r"
    
        i=$(((i + 1) % 4))
        sleep 1
    
      done
    
      echo -ne "Searching for: \e[33m\e[1m$query\e[0m    \n"
    
      urls=$(echo $results | jq '.webpage_url' | tr -d '"')
    
      OLDIFS=$IFS
      IFS=$'\n'
      results=($results)
      urls=($urls)
      IFS=$OLDIFS
    
      result=${results[$alternative]}
      url=${urls[$alternative]}
    #+end_src

*** Play video

    Finally the video is played via mpv.

    #+begin_src sh
      i=0  
    
      title=$(echo $result | jq '.fulltitle')
      title="${title%\"}"
      title="${title#\"}"
    
      echo -ne "Playing: \e[32m\e[1m$title\e[0m"
    
      mpv $url &> /dev/null
    #+end_src